San Bernardino killer Syed Farook may have radicalised after overseas trip

Syed Farook, one of the perpetrators of yesterday's San Bernardino massacre, once used an online dating site that he was looking for a good Muslim wife, and had "target practice" listed among his interests.

The purpose of the account, created when Farook was 22, was to find a wife. In the end, the 28-year-old died alongside his partner, Tasheen Malik, in a bloody shootout with police after the pair had slaughtered 14 and wounded as many as 21 others in the Inland Regional Centre.

Now police are investigating the possibility that at least 18 months before yesterday's rampage, the deeply religious, US-born Farook, who was described as "extremely quiet" by one of his colleagues, started to become radicalised.

A picture of Farook taken from a dating website. (AAP) ()

It's believed Farook, who had no criminal record, had been in contact with persons of interest to counter-terrorism authorities, but that he and Malik were not regarded as threats.

In July 2014, Farook returned from a trip to Saudi Arabia with Tashfeen Malik, the woman he would later marry. According to various media reports, Pakistan-born Malik, who was 27 when she died yesterday, entered the US on a visitor visa, meaning that the couple had a window of 90 days to tie the knot.

A year or so later, Malik gave birth to Farook's child – the pair dropped the six-month-old off at Farook's mother's house on their way to the Regional Inland Centre, where one of his victims would be a woman who used to attend the same mosque as Farook.

A photograph of Farook provided by the California Department of Motor Vehicles. ()

In what may indicate a critical change in Farook's life, an LA Times reports suggests the notably devout gunman stopped attending mosque shortly after holding an event there to celebrate his marriage to Malik.

"We were all shocked," Mustafa Kuko, director of the Islamic Centre of Riverside, told the LA Times.

"That that kind of nice person would do something like this … If you had told me that he had killed a bird, I would say, 'no way.'"

"We’re very involved in terms of trying to see if the motive was something inspired by a terrorist organization or directed by a terrorist organization, or whether he was self-radicalized," another source told the Times.

"I am not willing to go down that road just yet," the head of the FBI’s Los Angeles office, David Bowdich, told the press.

"We will go where the evidence takes us."

The FBI searches the Farook and Malik's house, where explosive devices and thousands of rounds of ammunition were found. (AAP) ()

At the couple's house, police found 12 pipe bombs, and thousands of rounds of ammunition – a stockpile big enough for a repeat performance.

During their rampage, the couple carried both assault rifles and pistols, as well as ammo vests, while three pipe bombs were found tied together and rigged to be detonated remotely, inside the Inland Regional Centre.

"I have absolutely no idea why he would do this" Farhan Kahn, Farook's brother-in-law, told the media yesterday.